In the related art, a system in which an image processing apparatus which may perform printing using a non-decolorable color material is used in combination with an image processing apparatus which may perform printing using a decolorable color material. Similarly, a system may include these apparatuses in integrated form. An image on a sheet as a decoloring target is stored in the image processing apparatus such as an image reading device which automatically reads the image using a scanner and an automatic document feeder (ADF).
As a light emitting unit of the scanner, a solid light emitting element such as an LED is used. It is understood that a light intensity of the solid light emitting element decreases along with a temperature rise. When an image which is formed using a decolorable color material that is decolored using heat, a temperature rise due to a heater becomes significant. When the original document is read using a scanner, there is a problem in that it is not possible to obtain a sufficient light intensity from the light emitting unit, and to perform normal reading, due to an influence of the temperature rise in the apparatus.